1. Field of the Invention
This invention pertains to water preheating systems, and in particular to a water preheating system utilizing the exhaust gases from a laundry dryer to preheat and store water for delivery upon demand to a conventional hot water heater.
2. Description of the Prior Art
It is well known that much heat energy is wasted by venting the hot exhaust gases of a laundry dryer directly into the atmosphere. With heating costs rising year after year it is recognized that what was once unwanted waste heat must now be put to better use.
In the commercial setting of a laundry or laundromat, there have been proposed complex schemes for recovering some of the heat energy of laundry dryer exhaust which would otherwise be lost. These schemes often employ relatively complex and expensive devices which become practical only under the economy of scale. Such devices include those disclosed in U.S. Pat. Nos. 3,050,867 to Friedman, issued Aug. 28, 1962; 4,161,214 to Wendel, issued July 17, 1979; and 4,275,510 to George, issued June 30, 1981. All of these systems are designed to work with a plurality of individual dryers. Common to each of the systems is a closed loop, pumped fluid heat removal circuit, employing individual heat exchangers disposed on or within the existing laundry dryer exhaust vents.
Because of their relative complexity and cost the heat removal systems of the prior art are unworkable in the average household laundry. In the household environment the cost of the heat recovery equipment must be kept to a minimum so that the system will "pay for itself" after only a few number of years. To keep costs to a minimum a heat recovery system for household use should be compatible with the homes existing plumbing. In addition, it is highly desirable that such a system be economically manufactured, preferably so as to be incorporated into a water heater manufacturer's line of products without the need to make drastic changes in existing manufacturing equiment and tooling. This invention will adapt to the bottom of existing hot water tanks now in production with only a slight modification.
Such a device would fill a growing need for home energy conservation products and would save countless dollars in wasted fuel now escaping through exhaust vents across the country.